9360 DE w/ Ubuntu 18.04 Won't Work With 2ndary Display Only

I upgraded to 18.04, and am using the default desktop setup (Xorg/Gnome) and at first, using my external display and disabling the laptop display works fine. However, after unplugging the thunderbolt dock (updated WD15) and plugging it back in, the external display doesn't come back unless I enable both displays, or delete ~/.config/monitors.xml

Whether I use xrandr or gnome settings, I get the same results. I'm using all of the workaround dell packages except dino2-mlk-meta, as that results in un-accelerated video decoding in browsers (very high CPU on youtube and such).